It is necessary for a number of applications to evaporate a liquid in a gas flow and to mix the evaporated liquid with the gas flow. For example, the introduction of a liquid fuel into the exhaust gas flow is considered for use in exhaust systems of internal combustion engines, for example, in order to bring about a rise in temperature in the exhaust system by means of a catalytic converter arranged downstream. Further, SCR systems are known in which a reducing agent is introduced into the exhaust gas flow upstream of an SCR catalytic converter, where SCR denotes Selective Catalytic Reduction. The reducing agent is preferably introduced in the liquid form and must evaporate as extensively as possible until it reaches the SCR catalytic converter and must be mixed with the exhaust gas flow as homogeneously as possible. An aqueous urea solution is typically considered for use as the reducing agent. The urea can be converted into ammonia and carbon dioxide in the process by thermolysis and subsequent hydrolysis. Reduction of nitrogen oxides into nitrogen and water can thus be achieved in the SCR catalytic converter.
Mixers or mixing devices of the type mentioned in the introduction are used to improve the evaporation and mixing of the respective liquid in the respective gas flow.
A mixer, which has a plurality of guide blades arranged in a star-shaped pattern, is known from DE 10 2011 111 765 A1. All guide blades are separate shaped sheet metal bodies, which are inserted in a star-shaped pattern into a cylindrical retaining ring and are welded to the retaining ring radially on the outside. All guide blades are connected with one another via a central weld joint radially on the inside. The effort needed to manufacture such a mixer is comparatively great, because a plurality of individual parts must be assembled and fitted together.